Abstract:
Animal Production in Australia Vol. 15 POLYPHENOLS IN LEAF PROTEIN CONCENTRATE DIETS FOR POULTRY D. R. MCKENZIE* and G. N. JHAM* Leaf protein concentrate (LPC) is produced commercially in some countries and has potential forproduction in Australia (McKenzie 1977). Although leaf protein has more sulphur amino acids than soya bean protein, experiments in these laboratories with chickens and by Hove et al (1974) with weanling rats have shown that sulphur amino acids appear less available in leaf protein than in soya bean protein. Pirie (1978) suggested that this reduced availability was due to scarce methionine acting as a methyl donor to facilitate excretion of polyphenols present in LPC diets. We tested this hypothesis for chickens by investigating whether choline as a methyl donor had a sparing effect on the requirements for sulphur amino acids. LPC was prepared by maceration of fresh young lucerne followed by auice expression in a press. Approximately one hour was allowed between juice expression and steam coagulation of LPC permitting polyphenylase activity to increase polyphenols in the LPC. One hundred and twenty Australorp/White leghorn cross cockerels were housed in battery brooders in a 4 x 2 x 3 factorial experiment. Chickens were fed a wheat based diet with soyabean meal (SBM) or LPC providing two thirds of dietary protein in a diet with 18% crude protein. In addition to a vitamin and mineral supplement 1.5% of choline was added to the basal diet. One of the dietary factors varied was protein The second SUppleItIentj LPC or SBM with or without 1% of additional choline. dietary factor varied was added methionine; zero or added. Initially methionine addition was 0.03% of diet (period I) and increased to 0.06% at age 21 days (period 2). Chickens were introduced to experimental diets at 11 days and weight gain and feed consumption was recorded during age 15 to 26 days. Protein efficiency ratios (PER's) were calculated as live weight gain per dry weight of crude protein in feed consumed. The high polyphenol LPC diets as expected gave much lower PER's than did SBM diets (P < 0.01). This depressed PER was overcome by choline addition with O&06% methionine. Thus choline spares methionine in the LPC, but not the SBM diet and supports the view that polyphenols in LPC increase requirement for sulphur amino acids. HOVE, E-L., LOHREY, E., URS, M.K. and ALLISON, R.M. (1974).Br. J. Nutr. 2: MCKENZIE, D.R. (1977). 147, Aust. J. of Exptal. Ag. and An. Hus.B 17 : 268. PIRIE, N.W. (1978). 'Leaf Protein and other aspects of fodder fractionation' p-86 (Cambridge University Press, Cambridge). *Department of Biological and Chemical Sciences, Bendigo C.A.E., Bendigo, Victoria 3550.